1. Field of the Invention
This invention relates to guidance systems and, more particularly, to guidance systems, such as are used in welding wherein a probe senses a welding path and then controls one or more positioning motors to position or change the position of the probe and the welding head to conform to the change or deviation detected by the probe.
2. Description of the Prior Art
Probes to detect a change or deviation in a path or welding seam are old and well-known in the art as shown, for example, in the Morehead U.S. Pat. No. 3,171,012.
Such probes have a shaft with a tip or sensing surface which engages the surface(s) defining the seam or joint and follows the same.
Changes or deviations in the path or seam are sensed by the tip and transmitted to appropriate switches operated by the remote end of the shaft, which switches turn a motor on or off to move the probe and/or the welding head in a direction, vertically and/or horizontally, as the case may be, to correct for the change or deviation sensed by the probe.
The switches either actuate or deactuate the positioning motor(s), i.e., turn them on or off, respectively, and when actuated, they operate at a single speed to position the probe and/or slave without regard to the magnitude or duration of the change or deviation detected.
While such probes and guidance systems exhibited marked improvement over systems known or suggested prior thereto, they have the disadvantage of not making proper corrections (and, therefore, proper welds) where a large correction or deviation is required, especially when of relatively short duration, i.e., short in the direction of longitudinal or basic travel of the probe and slave or welding head.
The last problem arises because the probe is over the deviation and signalling a new response before the slave has completed its correction for the prior deviation.
Similarly, if the change is of great magnitude, even if ultimately the new direction or result (correction) is utilized for some time, the response may be too slow and the slave may follow off course for some time, thus providing, for example, an inadequate, or, at least, not the best possible weld or other result.